The widow of a former ISIS leader was accused Monday of taking part in the abduction of Kayla Jean Mueller, the humanitarian aid worker from Arizona who was kidnapped in Syria in 2013 and died last year.
Federal prosecutors filed the charges against a 25-year-old Iraqi woman, Nisreen Assad Ibrahim Bahar, also known as Umm Sayyaf. She was married to Abu Sayyaf, a senior ISIS leader who was killed last May in a firefight with U.S. forces.
The Justice Department said she is in Iraqi custody for terrorism-related activities.
"We fully support the Iraqi prosecution of Sayyaf and will continue to work with the authorities there to pursue our shared goal of holding Sayyaf accountable for her crimes," said John Carlin, assistant attorney general in charge of the Justice Department's National Security Division.
See photos of Kayla Mueller:
Kayla Jean Mueller -- ISIS Hostage, Kayla Mueller
Widow of ISIS leader charged with role in Kayla Mueller's kidnapping
Courtesy: Mueller Family
#Obama confirms death of American #ISIS #hostage Kayla Mueller; Private Message from ISIS sent to Parents of ISIS Hostage, Kayla Mueller, Confirms Her Death http://read.bi/16QUgjt
Statement from the White House on the death of Kayla Mueller
Parents of #ISIS hostage Kayla Mueller urge her captors to contact them. http://t.co/oYOzFBF62r http://t.co/DTkx9od38u
The Mueller family have released new pictures of Kayla. http://t.co/vk7warF4OQ
The parents of American Islamic State (ISIS) hostage Kayla Mueller, who the extremist group claims was killed Friday by a Jordanian airstrike on the Syrian city of Raqqa, are hopeful that their daughter is still alive. Carl and Marsha Mueller said in a statement on Friday, "This news leaves us concerned, yet, we are still hopeful that Kayla is alive." Mueller's parents urged ISIS to contact them privately, and to treat their daughter as a guest.
.@ejmontini: For Kayla Mueller's family, waiting is not a game http://t.co/TvtOCrgFJv http://t.co/GEaSQNdKKv
Prescott stricken by loss, uncertainty of Kayla Mueller's fate. via @RebekahLSanders
Family, others kept Kayla Mueller's capture a secret to protect her, @KarenBrown3TV reports http://t.co/bHlvjWYAqw http://t.co/noUUfRUS6m
Family of hostage Kayla Mueller breaks silence after #IslamicState claims: http://t.co/Dv5w7uOFwW | http://t.co/iSNja0KShX
JUST IN: ISIS sent Muellers an e-mail saying their daughter was dead and included a photo, David Martin reports; cause of death inconclusive
A local Palestinian man holds up a poster of slain ISIS hostage Kayla Mueller who worked in Palestine and was an activist with the International Solidarity Movement- a movement dedicated to supporting a free Palestinian state. In the Palestinian West Bank village of Bilin, west of Ramallah, the 10th anniversary of the popular resistance movement against the Israeli occupation was held on Friday afternoon. Israeli soldiers invaded the village on Friday, stopping protesters from marching into the olive orchards. Israeli soldiers assaulted Palestinians and international activists, beating them, spraying them with a chemical orange agent, as well as using hundreds of tear gas canisters. Live ammunition rounds were also fired at protesters, including sound bombs thrown at the feet of journalists. Journalists who were filming the protests were assaulted by Israeli soldiers as well. The village gained global notoriety when a decade ago locals as well as international activists would gather and organize weekly protests on Fridays, marching towards olive orchards and lands that were confiscated by the Israeli government to build illegal settlements and the separation barrier in the West Bank. The village gained even more popularity after one of its locals, Emad Burnat, filmed the Oscar-nominated film, Five Broken Cameras in which he showed the struggle of the Palestinian village against Israeli aggression. Scores of people, both Palestinian and international have been injured during weekly protests, the most infamous of whom was Basem Au Rahma who was killed in 2009 when a tear gas canister struck him in the chest. Two years later, in 2011, Jawaher Abu Rahma also died during a weekly protest after being hit with a tear gas canister. (Photo by Anna Ferensowicz/Pacific Press/LightRocket via Getty Images)
Palestinian protesters hold placard to protest against 'terrorism' on February 13, 2015 before a demonstration against Jewish settlements in the West Bank village of Bilin, west of Ramallah. The poster shows a picture of US aid worker Kayla Mueller, who died as a hostage of Islamic State (IS) group jihadists. (Photo credit ABBAS MOMANI/AFP/Getty Images)
Palestinian protesters hold placard to protest against 'terrorism' on February 13, 2015 before a demonstration against Jewish settlements in the West Bank village of Bilin, west of Ramallah. The posters show pictures of US aid worker Kayla Mueller, who died as a hostage of Islamic State (IS) group jihadists. (Photo credit ABBAS MOMANI/AFP/Getty Images)
Laura Spaeth looks at a memorial honoring American hostage Kayla Mueller on the corner of courthouse plaza in Prescott, Ariz., Tuesday, Feb. 10, 2015. Islamic State group reported Friday that Muller, whose 18-month captivity had largely been kept secret in an effort to save her, had died in a recent Jordanian airstrike targeting the militants. On Tuesday her parents and U.S. officials confirmed she was dead, although officials said they could not confirm how she died. (AP Photo/Felicia Fonseca)
A small memorial honoring American hostage Kayla Mueller is on display at a corner of courthouse plaza in Prescott, Ariz.,Tuesday, Feb. 10, 2015. Islamic State group reported Friday that Muller, whose 18-month captivity had largely been kept secret in an effort to save her, had died in a recent Jordanian airstrike targeting the militants. On Tuesday her parents and U.S. officials confirmed she was dead, although officials said they could not confirm how she died. (AP Photo/Felicia Fonseca)
An unidentified woman kneels near a makeshift memorial for Kayla Mueller, Thursday, Feb. 12, 2015, in Prescott, Ariz. Mueller, a 26-year-old American woman held by Islamic State militants, was confirmed dead, her parents and the Obama administration said Tuesday. (AP Photo/Brian Skoloff)
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"We will continue to pursue justice for Kayla and for all American victims of terrorism," he said.
Prosecutors said Umm Sayyaf threatened Mueller and two other women who were being held, "telling them she would kill them if they did not listen to her."
The FBI said in court documents filed in Alexandria, Virginia, that the captives were held in locked rooms, sometimes handcuffed, and that Mueller was sexually abused by ISIS leader Abu Bakr al-Baghdadi.
"Umm Sayyaf knew how Mueller was treated by Baghdadi when Mueller was held against her will in Sayyaf's home," prosecutors said.
Court documents filed Monday said Sayyaf and her husband "held young women who were sold or traded" to ISIS men.
The FBI said Umm Sayyaf was interviewed by FBI agents in Iraq in 2015. The agents said that she "admitted that her family belonged to al-Qaeda in Iraq" and that she took part in holding the women hostage on behalf of ISIS.
The agents said she told them that al-Baghdadi "owned" Mueller during the time of captivity at the Sayyaf home.
"The defendant admitted that 'owning' is equivalent to slavery," prosecutors said.
Mueller and another person traveled into northern Syria on Aug. 3, 2013. On their second full day in the country, they were kidnapped by ISIS soldiers. ISIS leaders notified the Mueller family of her death in an e-mail Feb. 7, 2015.